G.fast is a proposed protocol which is currently under development and is described (at least to some extent) in the ITU standards G.9700 and G.9701. For the purposes of the present application, the proposed G.fast protocol is considered to be a Digital Subscriber Line (DSL) technology and any modems operating in accordance with it are considered to be DSL modems.
Digital subscriber lines are lines (usually in the form of twisted copper pairs) with Digital Subscriber Line (DSL) modems operating at both ends (of the line). This permits data to be communicated over a line at much greater data rates than is achievable with old voice-band modems operating over the same line and is generally therefore referred to as “DSL broadband”. The DSL modems may operate in accordance with any of various DSL standards agreed by the International Telecommunication Union (ITU). Over time newer DSL standards have been (and are still being) developed which permit ever greater data transmission rates to be achieved over digital subscriber lines. For example VDSL2 (as described in ITU standard G.993.2) is currently the highest capability DSL protocol for use with short lines (e.g. from a street cabinet to an end user's premises) which are already commercially in operation in the United Kingdom, whilst G.fast is still currently under development with commercially available G.fast compliant modems expected to be available commercially shortly.
A significant reason for the ability of protocols such as VDSL2 and G.fast to achieve much higher bandwidths than those possible with protocols adapted for use over much longer line lengths (e.g. ADSL2+), is their use of much greater frequency bandwidth ranges. For example, ADSL2+ operates in the frequency range from approximately 120 KHz to about 2.2 MHz whilst G.fast operates with frequencies up to 100 MHZ (and planned to go much higher in the future) and likely starts at a frequency of up to 30 MHz (to avoid damaging adjacent VDSL2+ lines—which operate with frequencies of up to 30 MHz).
At these frequencies, the signals can travel over (and transmit significant amounts of data over) a range of different media in addition to the usual twisted copper wire pairs. For example, as well as being able to be carried over normal, unshielded twisted copper pairs as typically found in Public Switched Telephone Network (PSTN) access networks, they can also travel over the power lines within users' premises, internal Ethernet cables (e.g. category 5 “Ethernet cables”, etc.), television aerial co-axial cables, etc.
At present, broadband over DSL is supplied to a user premises using an approach/architecture in which a broadband connection is provided to and terminated at a single location (with a DSL modem located there) within a user's premises and then separate data connections are provided from that single location to other devices within the premises using any one or more different in house data distribution techniques such as Wi-Fi, wired Ethernet, powerline adapters, etc. A problem with this approach is that the different protocols used (e.g. G.fast to the DSL termination point, and an Ethernet over Powerline (e.g. as per the IEEE 1901 standard) from the DSL termination point to a user device located in another part of the premises) may cause interference to one another reducing the capabilities of both protocols and thus adversely affecting the quality (bandwidth, latency, jitter, stability/interruptions, etc.) of the data connection to the user device.